1. templates

2.  python; x.pyc

3.

def hist(x):
   counts = {}
   for i in x:
      try:
         counts[i] += 1
      except:
         counts[i] = 1
   return counts

print hist([5,2,1,12,2,12])  # {1: 1, 2: 2, 12: 2, 5: 1}

4.

class textfile:
   ntfiles = {}  ## added
   def __init__(self,fname):
      self.name = fname  # name 
      textfile.ntfiles[fname] = self  ## added
      self.fh = open(fname)  # handle for the file

a = textfile('x')
b = textfile('y')
print 'textfile names are', textfile.ntfiles.keys()  ## added
# ['y', 'x']
print "the number of text files open is", len(textfile.ntfiles)  ## added; 2